Multiple Point Gate Oxide Integrity Test Method and System for the Manufacture of Semiconductor Integrated Circuits

ABSTRACT

A method for testing a semiconductor wafer using an in-line process control, e.g., within one or more manufacturing processes in a wafer fabrication facility and/or test/sort operation. The method includes transferring a semiconductor wafer to a test station. The method includes applying an operating voltage on a gate of a test pattern on a semiconductor wafer using one or more probing devices. The method includes measuring a first leakage current associated with the operating voltage. If the measured first current is higher than a first predetermined amount, the device is an initial failure. If the measured first current is below the first predetermined amount, the device is subjected to a second voltage. The method includes applying the second voltage on the gate of the test pattern on the semiconductor wafer and measuring a second leakage current associated with the second voltage. If the second measured leakage current is higher than a second predetermined amount, the device is an extrinsic failure. If the second measured leakage current is below the second predetermined amount, the device a good device. The method provides a way to monitor gate oxide integrity and/or process stability using extrinsic measurements according to a specific embodiment. The method includes determining a breakdown voltage associated with the second measured leakage value. In a preferred embodiment, the second measured leakage current is characterized as extrinsic information and the breakdown voltage is characterized as intrinsic information.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application claims the benefit and priority under 35 U.S.C. 119 (e)of U.S. Non-Provisional application Ser. No. 11/227,182, filed 14 Sep.2005, entitled “Multiple Point Gate Oxide Integrity Test Method andSystem for the Manufacture of Semiconductor Integrated Circuits,” whichis now allowed, the contents of which are herein incorporated byreference in their entirety for all purposes.

The present application also incorporates by reference the commonlyassigned U.S. Non-provisional application Ser. No. ______ (AttorneyDocket No.: 021653-018900US (SMIC Docket No.: 1-05-375)) in theirentirety for all purposes.

BACKGROUND OF THE INVENTION

The present invention is directed to integrated circuits and theirprocessing for the manufacture of semiconductor devices. Moreparticularly, the invention provides a method and device for testing agate oxide integrity for semiconductor integrated circuit devices, butit would be recognized that the invention has a much broader range ofapplicability.

Integrated circuits have evolved from a handful of interconnecteddevices fabricated on a single chip of silicon to millions of devices.Conventional integrated circuits provide performance and complexity farbeyond what was originally imagined. In order to achieve improvements incomplexity and circuit density (i.e., the number of devices capable ofbeing packed onto a given chip area), the size of the smallest devicefeature, also known as the device “geometry”, has become smaller witheach generation of integrated circuits.

Increasing circuit density has not only improved the complexity andperformance of integrated circuits but has also provided lower costparts to the consumer. An integrated circuit or chip fabricationfacility can cost hundreds of millions, or even billions, of U.S.dollars. Each fabrication facility will have a certain throughput ofwafers, and each wafer will have a certain number of integrated circuitson it. Therefore, by making the individual devices of an integratedcircuit smaller, more devices may be fabricated on each wafer, thusincreasing the output of the fabrication facility. Making devicessmaller is very challenging, as each process used in integratedfabrication has a limit. That is to say, a given process typically onlyworks down to a certain feature size, and then either the process or thedevice layout needs to be changed. Additionally, as devices requirefaster and faster designs, process including testing limitations existwith certain conventional processes and testing procedures for waferreliability.

An example of such test procedure is commonly called wafer levelreliability testing, commonly called WLR. In particularly, WLR has beenmore and more popular in process control due to the lower overall costand the shorter cycle time for process improvement. Among the many WLRtest methods, the ramp tests (voltage as well as current) take muchshorter time than the traditional methods, for example, time-dependentdielectric breakdown (TDDB) testing, and isothermal EM (Iso-EM) test forthe FEOL (Front-End Of Line) and BEOL (Back-End Of Line) process,respectively. In conventional GOI (Gate Oxide Integrity) V-ramp tests,we stress ramp voltage to detect breakdown voltage (Vbd) and from theVbd values, we divide the failures into various categories.

As the technology marches into the sub-90 nm era, the gate oxide becomesthinner (<12 Å) for MOS transistors, and the leakage current increasessharply. GOI testing becomes very difficult or even impossible. That is,larger structures cannot be used for testing. Additionally, smallerstructures are often difficult to test efficiently and accurately. Foraccurate test results using smaller samples, increased test times mustoften occur. These and other limitations can be found throughout thepresent specification and more particularly below.

From the above, it is seen that an improved technique for processingsemiconductor devices is desired.

SUMMARY OF INVENTION

According to the present invention, techniques directed to integratedcircuits and their processing for the manufacture of semiconductordevices are provided. More particularly, the invention provides a methodand device for testing a gate oxide integrity for semiconductorintegrated circuit devices. More particularly, the invention provides amethod and device for determining intrinsic characteristics of an MOSdevice using extrinsic measurements of one or more parameters. Althoughthe invention has been described in terms of gate oxide integrity of MOSdevices, it would be recognized that the invention has a much broaderrange of applicability.

In a specific embodiment, the present invention provides a method formanufacturing a semiconductor integrated circuit device, e.g., MOStransistor, CMOS transistors, bipolar. The method includes providing asemiconductor wafer free from patterns, e.g., bulk, silicon oninsulator. The method includes processing the semiconductor wafer withone or more processes to form one more patterns thereon. The methodincludes applying an operating voltage on a gate of a test patterndevice on the semiconductor wafer using one or more probing devices,which are coupled to a probing system. The method includes measuring afirst leakage current associated with the operating voltage anddetermining if the measured first current is higher than a firstpredetermined amount. The method also includes categorizing the deviceas an initial failure if the measured first current is higher than thefirst predetermined amount. The method includes storing a firstindication associated with the initial failure if the device has beencategorized as the initial failure. The method includes applying asecond voltage to the gate of the test pattern device of thesemiconductor wafer if the measured first current is below the firstpredetermined amount. The method includes measuring a second leakagecurrent associated with the second voltage using one or more probingdevices. The method includes categorizing the device as an extrinsicfailure if the second measured leakage current is higher than a secondpredetermined amount. The method includes storing a second indicationassociated with the extrinsic failure if the device has been categorizedas the extrinsic failure and categorizing the device as a good device ifthe second measured leakage current is below the second predeterminedamount. The method includes storing a third indication associated withthe good device, if the device has been categorized as the good device.

In an alternative specific embodiment, the present invention provides amethod for testing a semiconductor wafer using a multi-point probingprocess, which may be in-line or the like. The method includes providinga semiconductor wafer, including one more patterns thereon. The methodincludes applying an operating voltage on a gate of a test patterndevice on the semiconductor wafer using one or more probing devices. Themethod includes measuring a first leakage current associated with theoperating voltage. The method includes determining if the measured firstcurrent is higher than a first predetermined amount. The method alsoincludes categorizing the device as an initial failure if the measuredfirst current is higher than the first predetermined amount. The methodstores a first indication associated with the initial failure if thedevice has been categorized as the initial failure. The method alsoincludes applying a second voltage to the gate of the test patterndevice of the semiconductor wafer if the measured first current is belowthe first predetermined amount. The method includes measuring a secondleakage current associated with the second voltage using one or moreprobing devices. The method includes categorizing the device as anextrinsic failure if the second measured leakage current is higher thana second predetermined amount. The method also stores a secondindication associated with the extrinsic failure if the device has beencategorized as the extrinsic failure. The method includes categorizingthe device as a good device if the second measured leakage current isbelow the second predetermined amount and storing a third indicationassociated with the good device, if the device has been categorized asthe good device.

In yet an alternative embodiment, the present invention provides asystem for testing a semiconductor wafer using an in-line processcontrol. The system has one or more computer readable memories. Thesystem includes one or more codes (e.g., computer codes) directed toapplying an operating voltage on a gate of a test pattern on asemiconductor wafer using one or more probing devices. One or more codesis directed to measuring a first leakage current associated with theoperating voltage. One or more codes is directed to determining if themeasured first current is higher than a first predetermined amount toindicate an initial failure. One or more codes is directed todetermining if the measured first current is below the firstpredetermined amount to indicate that the device is subjected to asecond voltage. One or more codes is directed to applying the secondvoltage on the gate of the test pattern on the semiconductor wafer. Oneor more codes is directed to measuring a second leakage currentassociated with the second voltage. One or more codes is directed todetermine if the second measured leakage current is higher than a secondpredetermined amount to indicate the device is an extrinsic failure. Thesystem also includes one or more codes directed to determine if thesecond measured leakage current is below the second predetermined amountto indicate the device a good device.

Depending upon the specific embodiment, there can be other variationsand modifications to any of the embodiments noted herein. In a preferredembodiment, the test pattern is associated with a gate oxide integritytest. In a specific embodiment, the test pattern comprises a pluralityof electrodes formed overlying a gate dielectric layer, which isoverlying an active region. The test pattern has a first predeterminedlength and a first predetermined width. In a preferred embodiment, thetest pattern is provided on a scribe region of the semiconductor wafer.In one or more embodiments, the method includes determining a calculatedbreakdown voltage associated with the second measured current valueusing a plot of values represented by leakage current against breakdownvoltage for at least two groupings of devices.

In a preferred embodiment, the present invention provides a method andsystem for multi-point (e.g., double-point) GOI test that canefficiently judge failure modes by testing only two points. We canmeasure leakage currents at only two voltages, which are the cut pointsof mode A-B and B-C, instead of the whole ramped voltages to save timeand cost with the same test effectiveness according to a specificembodiment. By correlating leakage current at extrinsic field to thebreakdown voltage, we can also evaluate the intrinsic reliability evenif the samples are not subjected to actual breakdown according to aspecific embodiment.

Many benefits are achieved by way of the present invention overconventional techniques. For example, the present technique provides aneasy to use process that relies upon conventional technology. In someembodiments, the method provides a way to achieve higher device yieldsin dies per wafer. Additionally, the method provides a process that iscompatible with conventional process technology without substantialmodifications to conventional equipment and processes. In a specificembodiment, the present method and system can provide an easy way totest the integrity of gate oxide of one or more gate transistor devicesprovided on a test pattern. Alternatively, the present method and systemcan provide a way of determine intrinsic information using extrinsictest information according to a specific embodiment. In preferredembodiments, the present invention provides methods and systems thatallow for determining a breakdown voltage of, for example, an MOS deviceusing empirical information derived from test patterns using one or moreprobe structures. Depending upon the embodiment, one or more of thesebenefits may be achieved. These and other benefits will be described inmore throughout the present specification and more particularly below.

Various additional objects, features and advantages of the presentinvention can be more fully appreciated with reference to the detaileddescription and accompanying drawings that follow.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a simplified flow diagram of an overall testing methodaccording to an embodiment of the present invention;

FIG. 2 is a simplified flow diagram of an alternative testing methodaccording to an alternative embodiment of the present invention;

FIG. 3 is a simplified flow diagram of yet an alternative testing methodaccording to an alternative embodiment of the present invention;

FIG. 4 is a simplified flow diagram of still an alternative testingmethod according to an embodiment of the present invention;

FIG. 5 is a simplified diagram of a testing system according to anembodiment of the present invention;

FIGS. 6 and 6A are simplified diagrams of a computer system according toan embodiment of the present invention;

FIGS. 7 through 13 are simplified diagrams of certain experimentalresults according to embodiments of the present invention.

DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS

According to the present invention, techniques directed to integratedcircuits and their processing for the manufacture of semiconductordevices are provided. More particularly, the invention provides a methodand device for testing a gate oxide integrity for semiconductorintegrated circuit devices. More particularly, the invention provides amethod and device for determining intrinsic characteristics of an MOSdevice using extrinsic measurements of one or more parameters. Althoughthe invention has been described in terms of gate oxide integrity of MOSdevices, it would be recognized that the invention has a much broaderrange of applicability.

In a specific embodiment, a method for manufacturing a semiconductordevice and categorizing one or more characteristics using a probingtechnique according to an alternative embodiment of the presentinvention may be outlined as follows.

1. Providing a semiconductor wafer with one more patterns thereon;

2. Apply an operating voltage on a gate of a test pattern device on thesemiconductor wafer using one or more probing devices;

3. Measure a first leakage current associated with the operatingvoltage;

4. Determine if the measured first current is higher than a firstpredetermined amount;

5. Categorize the device as an initial failure if the measured firstcurrent is higher than the first predetermined amount;

6. Storing a first indication associated with the initial failure if thedevice has been categorized as the initial failure;

7. Apply a second voltage to the gate of the test pattern device of thesemiconductor wafer if the measured first current is below the firstpredetermined amount;

8. Measure a second leakage current associated with the second voltageusing one or more probing devices;

9. Categorize the device as an extrinsic failure if the second measuredleakage current is higher than a second predetermined amount;

10. Store a second indication associated with the extrinsic failure ifthe device has been categorized as the extrinsic failure;

11. Categorize the device as a good device if the second measuredleakage current is below the second predetermined amount;

12. Store a third indication associated with the good device, if thedevice has been categorized as the good device;

13. Determine if the second measure current value is within apredetermined range to indicate if one or more processes is stable;

14. Determine a breakdown voltage associated with the second measuredcurrent value;

15. Determine if the breakdown voltage is within a breakdown voltagepredetermined value; and

16. Perform other steps, as desired.

The above sequence of steps provides a method according to an embodimentof the present invention. As shown, the method uses a combination ofsteps including a way of manufacturing and testing a semiconductor waferfor gate oxide integrity according to an embodiment of the presentinvention. Additionally, the method provides a way to monitor gate oxideintegrity and/or process stability using extrinsic measurementsaccording to a specific embodiment. In other embodiments, the presentmethod and system provide for a way to determine an intrinsiccharacteristic (e.g., breakdown voltage) using one or more extrinsiccharacteristics, which are measurable, according to a specificembodiment. Other alternatives can also be provided where steps areadded, one or more steps are removed, or one or more steps are providedin a different sequence without departing from the scope of the claimsherein. Details of the present method and structure can be foundthroughout the present specification and more particularly below.

FIG. 1 is a simplified flow diagram of an overall testing method 100according to an embodiment of the present invention. This diagram ismerely an example, which should not unduly limit the scope of the claimsherein. One of ordinary skill in the art would recognize othervariations, modifications, and alternatives. In a specific embodiment,the method begins by providing a semiconductor wafer with one morepatterns thereon. The semiconductor substrate often has one or moredevices, including one or more patterned MOS transistors thereon. Asmerely an example, the semiconductor substrate can also be capable ofbeing tested using the “Procedure for the Wafer-Level Testing of ThinDielectrics,” JEDEC Standard, JESD35-A published April 2001, which ishereby incorporated by reference herein, but can also be subjected toother testing techniques.

In a specific embodiment, the present method includes applying anoperating voltage (step 101) on a gate of a test pattern device on thesemiconductor wafer using one or more probing devices. In a specificembodiment, the probing devices can include those by Electroglas, Inc.of 5729 Fontanoso Way, San Jose, Calif. 95138-1015, as well as othercompanies, depending upon the application.

As further shown, the method measures (step 103) a first leakage currentassociated with the operating voltage. In a specific embodiment, theoperating voltage can be any conventional operating voltage such as 3.3volts, 2.5 volts, and others, depending upon the application. The methoddetermines (step 105) if the measured first current is higher than afirst predetermined amount. In a specific embodiment, the firstpredetermined amount is a limit provided by an operating specification.Depending upon the embodiment, the method categorizes the device as aninitial failure (step 107) if the measured first current is higher thanthe first predetermined amount. Additionally, the method stores a firstindication associated with the initial failure if the device has beencategorized as the initial failure. Depending upon the embodiment, thefirst indication can be stored in one or more memories coupled to thewafer probing device.

In a specific embodiment, the method applies a second voltage (step 109)to the gate of the test pattern device of the semiconductor wafer if themeasured first current is below the first predetermined amount. Themethod measures (step 111) a second leakage current associated with thesecond voltage using one or more probing devices according to a specificembodiment. As shown, the method categorizes (step 115) the device as anextrinsic failure if (step 113) the second measured leakage current ishigher than a second predetermined amount, which is an amount determinedby an operating specification. The method stores a second indicationassociated with the extrinsic failure if the device has been categorizedas the extrinsic failure according to a specific embodiment. Dependingupon the embodiment, the second indication can be stored in one or morememories coupled to the wafer probing device.

In a specific embodiment, the method categorizes (step 117) the deviceas a good device if the second measured leakage current is below thesecond predetermined amount. In a specific embodiment, the method storea third indication associated with the good device, if the device hasbeen categorized as the good device. Depending upon the embodiment, thethird indication can be stored in one or more memories coupled to thewafer probing device. As also shown, the method can stop, step 117, ifit is determined that the device has an intrinsic failure. Furtherdetails of the present method can be found throughout the presentspecification and more particularly below. Of course, there can be othermodifications, alternatives, and variations.

In an alternative embodiment, the method accumulates (step 119)information (e.g., data) to form a control limit for a specification. Ina preferred embodiment, the method determines current at a certainvoltage, which is applied, to the MOS device. The method determines suchdata for a plurality of devices to obtain the control limit. The methoddetermines, as an example, if the second measure current value is withina predetermined range to indicate if one or more processes is stable(step 121), using the control limit and empirical data according to aspecific embodiment. Further details of the present method can be foundthroughout the present specification and more particularly below. Ofcourse, there can be other modifications, alternatives, and variations.

In an alternative specific embodiment, the method forms a predictiverelationship (step 123) by associating different breakdown voltages andrelated current and voltage data. In a preferred embodiment, the presentmethod determines intrinsic device information such as breakdown voltageusing extrinsic current/voltage data. Once the predictive relationshiphas been established, the method determines a breakdown voltageassociated with the second measured current value according to aspecific embodiment. The method determines if the breakdown voltage iswithin a breakdown voltage predetermined value, step 125, using thepredictive relationship. Further details of the present method can befound throughout the present specification and more particularly below.Of course, there can be other modifications, alternatives, andvariations.

The above sequence of steps provides a method according to an embodimentof the present invention. As shown, the method uses a combination ofsteps including a way of manufacturing and testing a semiconductor waferfor gate oxide integrity according to an embodiment of the presentinvention. Additionally, the method provides a way to monitor gate oxideintegrity and/or process stability using extrinsic measurementsaccording to a specific embodiment. In other embodiments, the presentmethod and system provide for a way to determine an intrinsiccharacteristic (e.g., breakdown voltage) using one or more extrinsiccharacteristics, which are measurable, according to a specificembodiment. Other alternatives can also be provided where steps areadded, one or more steps are removed, or one or more steps are providedin a different sequence without departing from the scope of the claimsherein.

In a specific embodiment, a method for manufacturing a semiconductordevice and categorizing one or more characteristics using a probingtechnique according to an alternative embodiment of the presentinvention may be outlined as follows and referenced by a simplified flowdiagram 200 of FIG. 2.

1. Provide (step 201) a semiconductor wafer free from patterns;

2. Process (step 203) the semiconductor wafer with one or more processesto form one more patterns thereon;

3. Apply (step 205) an operating voltage on a gate of a test patterndevice on the semiconductor wafer using one or more probing devices;

4. Measure (step 207) a first leakage current associated with theoperating voltage;

5. Determine (step 209) if the measured first current is higher than afirst predetermined amount;

6. Categorize the device as an initial failure (step 211) if themeasured first current is higher than the first predetermined amount;

7. Storing a first indication (step 213) associated with the initialfailure if the device has been categorized as the initial failure;

8. Apply (step 215) a second voltage to the gate of the test patterndevice of the semiconductor wafer if the measured first current is belowthe first predetermined amount;

9. Measure a second leakage current (step 217) associated with thesecond voltage using one or more probing devices;

10. Categorize the device as an extrinsic failure (step 221) if thesecond measured leakage current is higher than a second predeterminedamount;

11. Store a second indication (step 223) associated with the extrinsicfailure if the device has been categorized as the extrinsic failure;

12. Categorize the device as a good device (step 225) if the secondmeasured leakage current is below the second predetermined amount;

13. Store a third indication (step 227) associated with the good device,if the device has been categorized as the good device; and

14. Perform other steps (step 229), as desired.

The above sequence of steps provides a method according to an embodimentof the present invention. As shown, the method uses a combination ofsteps including a way of manufacturing and testing a semiconductor waferfor gate oxide integrity according to an embodiment of the presentinvention. Other alternatives can also be provided where steps areadded, one or more steps are removed, or one or more steps are providedin a different sequence without departing from the scope of the claimsherein. As shown, FIG. 2 is the simplified flow diagram 200 of thealternative testing method according to the alternative embodiment ofthe present invention. This diagram is merely an example, which shouldnot unduly limit the scope of the claims herein. One of ordinary skillin the art would recognize other variations, modifications, andalternatives. Details of the present method and structure can be foundthroughout the present specification and more particularly below.

In an alternative specific embodiment, the present invention provides amethod for manufacturing one or more semiconductor wafers using anin-line process control, which has been briefly outlined below andreferenced by a simplified flow diagram 300 of FIG. 3.

1. Transfer (step 301) an in-process semiconductor wafer to a teststation;

2. Apply (step 305) an operating voltage on a gate of a test patternwith an associated device on a semiconductor wafer using one or moreprobing devices;

3. Measure a first leakage current (step 307) associated with theoperating voltage;

4. If (step 309) the measured first current is higher than a firstpredetermined amount, categorize the device as an initial failure (step311) and store indication associated with the initial failure (step313);

5. If the measured first current is below the first predeterminedamount, categorize (step 315) the device for a second voltage testprocess;

6. Apply (step 317) the second voltage using the second voltage testprocess on the gate of the test pattern on the semiconductor wafer;

7. Measure (step 319) a second leakage current associated with thesecond voltage;

8. If (step 321) the second measured leakage current is higher than asecond predetermined amount, categorize the device as an extrinsicfailure (step 323) and store indication associated with the extrinsicfailure (step 325);

9. If the second measured leakage current is below the secondpredetermined amount, categorize the device as a good device (step 327);

10. Process (step 329) the second measure current value within apredetermined range formed using data from current/voltage measurements;

11. Determine if (step 331) the second measure current value is withinthe predetermined range to indicate if one or more processes is stable(step 333);

12. Determine if (step 331) the second measure current value is withinthe predetermined range to indicate if one or more processes is unstable(step 337);

13. Process (step 335) the second measured current value againstcurrent/voltage measurements to determine a breakdown voltage;

14. Determine the breakdown voltage (step 339) associated with thesecond measured current value;

15. Determine if the breakdown voltage is within a breakdown voltagepredetermined value (step 341); and

16. Perform other steps (step 343), as desired.

The above sequence of steps provides a method according to an embodimentof the present invention. As shown, the method uses a combination ofsteps including a way of manufacturing and testing a semiconductor waferfor gate oxide integrity according to an embodiment of the presentinvention. As shown, the method also provides a way of determining abreakdown voltage using a current value according to an embodiment ofthe present invention. Other alternatives can also be provided wheresteps are added, one or more steps are removed, or one or more steps areprovided in a different sequence without departing from the scope of theclaims herein. Details of the present method and structure can be foundthroughout the present specification and more particularly below. Asshown, FIG. 3 is the simplified flow diagram 300 of yet the alternativetesting method according to an alternative embodiment of the presentinvention. This diagram is merely an example, which should not undulylimit the scope of the claims herein. One of ordinary skill in the artwould recognize other variations, modifications, and alternatives.Further details of the present invention can be found throughout thepresent specification and more particularly below.

In an alternative specific embodiment, the present invention provides amethod for manufacturing one or more semiconductor wafers using anin-line process control, which has been briefly outlined below andreferenced by a simplified flow diagram 400 of FIG. 4.

1. Transfer (step 401) an in-process semiconductor wafer to a teststation;

2. Apply (step 405) an operating voltage on a gate of a test patternwith an associated device on a semiconductor wafer using one or moreprobing devices;

3. Measure (step 407) a first leakage current associated with theoperating voltage;

4. If (step 409) the measured first current is higher than a firstpredetermined amount, categorize the device as an initial failure (step411) and stores an indication associated with the initial failure (step413);

5. If the measured first current is below the first predeterminedamount, categorize (step 415) the device for a second voltage testprocess;

6. Apply (step 417) the second voltage using the second voltage testprocess on the gate of the test pattern on the semiconductor wafer;

7. Measure (step 419) a second leakage current associated with thesecond voltage;

8. If (step 421) the second measured leakage current is higher than asecond predetermined amount, categorize the device as an extrinsicfailure (step 425) and store an indication associated with the extrinsicfailure (step 427);

9. If the second measured leakage current is below the secondpredetermined amount, categorize the device as a good device (step 423)and store (step 429) an indication associated with the good device;

10. Determine if (steps 431, 433) the second measure current value iswithin a predetermined range to indicate if one or more processes isstable (step 435) or unstable (step 437);

11. Determine (step 441, 445) a breakdown voltage associated with thesecond measured current value;

12. Determine (step 445) if the breakdown voltage is within a breakdownvoltage predetermined value; and

13. Perform other steps (step 447), as desired.

The above sequence of steps provides a method according to an embodimentof the present invention. As shown, the method uses a combination ofsteps including a way of manufacturing and testing a semiconductor waferfor gate oxide integrity according to an embodiment of the presentinvention. As shown, the method also provides a way of determining abreakdown voltage using a current value according to an embodiment ofthe present invention. Other alternatives can also be provided wheresteps are added, one or more steps are removed, or one or more steps areprovided in a different sequence without departing from the scope of theclaims herein. As shown, FIG. 4 is the simplified flow diagram of stillthe alternative testing method according to the embodiment of thepresent invention. This diagram is merely an example, which should notunduly limit the scope of the claims herein. One of ordinary skill inthe art would recognize other variations, modifications, andalternatives. Details of the present method and structure can be foundthroughout the present specification and more particularly below.

FIG. 5 is a simplified diagram of a testing system 500 according to anembodiment of the present invention. This diagram is merely an example,which should not unduly limit the scope of the claims herein. One ofordinary skill in the art would recognize other variations,modifications, and alternatives. As shown, the test system includes atester 501 coupled to a probing unit 503 or one or more probing units.Each of the probing units includes test head 505 and other elements.Examples of such probing units are provided by Electroglas, Inc. of 5729Fontanoso Way, San Jose, Calif. 95138-1015, as well as other companies,depending upon the application. The tester and probing unit are oftenoverseen and controlled by one or more computer systems. Of course,there can be other variations, modifications, and alternatives. Detailsof these computing systems can be found throughout the presentspecification and more particularly below.

FIGS. 6 and 6A are simplified diagrams of a computer system 600, whichcouples to test system, according to an embodiment of the presentinvention. These diagrams are merely examples, which should not undulylimit the scope of the claims herein. One of ordinary skill in the artwould recognize other variations, modifications, and alternatives.Depending upon the specific embodiment, the computer system includes amicroprocessor and/controllers. In a preferred embodiment, the computersystem or systems include a common bus, oversees and performs operationand processing of information. As shown, the computer system includesdisplay device, display screen, cabinet, keyboard, scanner and mouse.Mouse and keyboard are representative “user input devices.” Mouseincludes buttons for selection of buttons on a graphical user interfacedevice. Other examples of user input devices are a touch screen, lightpen, track ball, data glove, microphone, and so forth.

The system is merely representative of but one type of system forembodying the present invention. It will be readily apparent to one ofordinary skill in the art that many system types and configurations aresuitable for use in conjunction with the present invention. In apreferred embodiment, computer system includes a Pentium™ class basedcomputer, running Windows™ NT operating system by Microsoft Corporationor Linux based systems from a variety of sources. However, the system iseasily adapted to other operating systems and architectures by those ofordinary skill in the art without departing from the scope of thepresent invention. As noted, mouse can have one or more buttons such asbuttons. Cabinet houses familiar computer components such as diskdrives, a processor, storage device, etc. Storage devices include, butare not limited to, disk drives, magnetic tape, solid-state memory,bubble memory, etc. Cabinet can include additional hardware such asinput/output (I/O) interface cards for connecting computer system toexternal devices external storage, other computers or additionalperipherals, which are further described below.

FIG. 6A is a more detailed diagram of hardware elements in the computersystem according to an embodiment of the present invention. This diagramis merely an example, which should not unduly limit the scope of theclaims herein. One of ordinary skill in the art would recognize manyother modifications, alternatives, and variations. As shown, basicsubsystems are included in computer system 600. In specific embodiments,the subsystems are interconnected via a system bus 385. Additionalsubsystems such as a printer 684, keyboard 688, fixed disk 689, monitor686, which is coupled to display adapter 692, and others are shown.Peripherals and input/output (I/O) devices, which couple to I/Ocontroller 681, can be connected to the computer system by any number ofmeans known in the art, such as serial port 687. For example, serialport 687 can be used to connect the computer system to a modem 691,which in turn connects to a wide area network such as the Internet, amouse input device, or a scanner. The interconnection via system busallows central processor 683 to communicate with each subsystem and tocontrol the execution of instructions from system memory 682 or thefixed disk 689, as well as the exchange of information betweensubsystems. Other arrangements of subsystems and interconnections arereadily achievable by those of ordinary skill in the art. System memory,and the fixed disk are examples of tangible media for storage ofcomputer programs, other types of tangible media include floppy disks,removable hard disks, optical storage media such as CD-ROMS and barcodes, and semiconductor memories such as flash memory,read-only-memories (ROM), and battery backed memory.

Although the above has been illustrated in terms of specific hardwarefeatures, it would be recognized that many variations, alternatives, andmodifications can exist. For example, any of the hardware features canbe further combined, or even separated. The features can also beimplemented, in part, through software or a combination of hardware andsoftware. The hardware and software can be further integrated or lessintegrated depending upon the application. Further details of certainmethods according to the present invention can be found throughout thepresent specification and more particularly below.

EXAMPLES

FIGS. 7 through 13 are simplified diagrams of certain experimentalresults according to embodiments of the present invention. Thesediagrams are merely examples, which should not unduly limit the scope ofthe claims herein. One of ordinary skill in the art would recognizeother variations, modifications, and alternatives.

It is also understood that the examples and embodiments described hereinare for illustrative purposes only and that various modifications orchanges in light thereof will be suggested to persons skilled in the artand are to be included within the spirit and purview of this applicationand scope of the appended claims.

Among the many WLR test methods, the ramp tests (voltage as well ascurrent) take much shorter time than the traditional methods [1,2]; wepropose the double-point GOI V-ramp (voltage ramp) further reduce testtime for WLRC.

In the fast WLR GOI tests, we can measure leakage currents at only twovoltages, which are the cut points of mode A-B and B-C [3], instead ofthe whole ramped voltages to save time/cost with the same testeffectiveness. FIG. 7 shows the typical I-V curves from two lots: Lot Bsuffers in-line problems and has a lower breakdown voltage than Lot A,which is normal.

From the I-V curves, we notice Lot B has a higher leakage current at 10MV/cm (which is gate oxide V-ramp test criteria for mode B in thiscase). This indicates that the leakage currents at certain voltage arerelated to the breakdown voltage. We can conclude that a higher currentwill lead to a lower breakdown voltage. This indicates a goodcorrelation between extrinsic and intrinsic reliability. So we can usethe operation voltage and 10 MV/cm as the test point to judge mode A andB failure, respectively. We can also use the current under 10 MV/cm toproject the intrinsic lifetime. This method is more sensitive on sampleswith small areas due to the lower leakage levels; thus, it is moresuitable for WLRC test. This test can save 70% testing time than theconventional V-ramp tests

Referring back to FIG. 7, we illustrated the typical I-V from two lots:Lot B suffers in-line problems and has a lower breakdown voltage thanLot A, which is normal. From the I-V curves, we notice Lot B has ahigher leakage current at 10 MV/cm (which is gate oxide V-ramp testcriteria for mode B in this case). This indicates that the leakagecurrents at certain voltage are related to the breakdown voltage, whichis confirmed by FIG. 8. We can conclude that a higher current will leadto a lower breakdown voltage. This indicates a good correlation betweenextrinsic and intrinsic reliability. So we can use the operation voltageand 10 MV/cm as the test point to judge mode A and B failure,respectively.

In a specific embodiment, the present method is more sensitive onsamples with small areas due to the lower leakage levels; thus, it ismore suitable for WLRC test (scribe lane test structure, for example:100*70 um2). Referring now to FIG. 9, which illustrates a Vbd 0.1% WLRCtrend chart and FIG. 10 is an 10.1%@10 MV/cm trend chart according to aspecific embodiment. Referring to these figures, we can find they havevery good consistence. From FIG. 11, we can find that the presentdouble-point method is very sensitive even for intrinsic oxideperformance. Vbd has a difference of only several volts, but I@10 MV/cmhas several tenfold difference. By the present double-point GOI testmethod, we can save 70% test time than the conventional V-ramp testsaccording to a specific embodiment. Of course, there can be othervariations, modifications, and alternatives.

We can also use the current under 10 MV/cm to project the intrinsicperformance of the device. As FIG. 12 indicates, we can get fit functionfrom real data for a given process and project breakdown voltageaccording to the current under 10 MV/cm. So, by correlating leakagecurrent at extrinsic field to the breakdown voltage, we can alsoevaluate the intrinsic reliability even if the device samples are notsubjected to actual breakdown. We can explain this correlation betweenleakage current at extrinsic field and the breakdown voltage fromtunneling current and effective oxide thinning by the followingrelationships.

Tunneling Current:

J=A*(Eox)²*exp(−B/Eox)  Equation (1)

where: Eox is the oxide electrical field.

Modeling oxide defects as “effective oxide thinning” by an amount ofΔXox is illustrated in the simplified diagram of FIG. 13. We have alsoprovided the relationship as follows:

VBD ² /RGXeff*exp(−GXeff/VBD)=τ₀  Equation (2)

where

-   -   R is the ramp rate; and    -   Xeff=Xox−ΔXox.        From the above equation, we can relate VBD with ΔXox. We relate        equation (1) and (2) to derive the equation for Vbd and J@ a        given stress voltage (V):

J˜AV ²/(Vbd[ln(V ² bd)]²)*exp[−Vbd*ln(V ² bd)/V]  Equation 3

As shown, the above example is merely an illustration and should notunduly limit the scope of the claims herein. One of ordinary skill inthe art would recognize many variations, modifications, andalternatives. In order to satisfy a desire of fast WLRC to reduce thecycle time of the product and the cost, we have provided new ramp testmethodologies in combination of the above methods and systems accordingto embodiments of the present invention. The double-point GOI tests areproved effective from production records. Of course, there can be othervariations, modifications, and alternatives.

REFERENCES

-   [1] Michel Depas, Tanya Nigan, and Marc M. Heyns, “Soft Breakdown of    Ultra-Thin Gate Oxide Layers”, IEEE Transactions on Electronic    Devices, Vol. 43, No. 9, September 1996, pp 1499-1504.-   [2] Eric S. Snyder, John Suchle, “Detecting Breakdown in Ultra-thin    Dielectrics Using a Fast Voltage Ramp”, International Integrated    Reliability Workshop Final Report, 1999, pp. 118-123.-   [3] C. Y. Chang, et al., Reliability of ultra-thin gate oxides for    ULSI devices, Microelectronics Reliability, 39, 553 (1999).

The various embodiments may be implemented as part of a computer systemand other test system, including computer codes. The computer system mayinclude a computer, an input device, a display unit, and an interface,for example, for accessing the Internet. The computer may include amicroprocessor. The microprocessor may be connected to a data bus. Thecomputer may also include a memory. The memory may include Random AccessMemory (RAM, e.g. DRAM, SRAM, Flash) and Read Only Memory (ROM). Thecomputer system may further include a storage device, which may be ahard disk drive or a removable storage drive such as a floppy diskdrive, optical disk drive, jump drive and the like. The storage devicecan also be other similar means for loading computer programs or otherinstructions into the computer system.

As used herein, the term ‘computer’ may include any processor-based ormicroprocessor-based system including systems using microcontrollers,digital signal processors (DSP), reduced instruction set circuits(RISC), application specific integrated circuits (ASICs), logiccircuits, and any other circuit or processor capable of executing thefunctions described herein. The above examples are exemplary only, andare thus not intended to limit in any way the definition and/or meaningof the term ‘computer’. The computer system executes a set ofinstructions that are stored in one or more storage elements, in orderto process input data. The storage elements may also hold data or otherinformation as desired or needed. The storage element may be in the formof an information source or a physical memory element within theprocessing machine.

The set of instructions may include various commands that instruct theprocessing machine to perform specific operations such as the processesof the various embodiments of the invention. The set of instructions maybe in the form of a software program. The software may be in variousforms such as system software or application software. Further, thesoftware may be in the form of a collection of separate programs, aprogram module within a larger program or a portion of a program module.The software also may include modular programming in the form ofobject-oriented programming. The processing of input data by theprocessing machine may be in response to user commands, or in responseto results of previous processing, or in response to a request made byanother processing machine.

Although specific embodiments of the present invention have beendescribed, it will be understood by those of skill in the art that thereare other embodiments that are equivalent to the described embodiments.Accordingly, it is to be understood that the invention is not to belimited by the specific illustrated embodiments, but only by the scopeof the appended claims.

1. A method for testing a semiconductor wafer using a multi-pointprobing process, the method comprising: providing a semiconductor wafer,including one more patterns thereon; applying an operating voltage on agate of a test pattern device on the semiconductor wafer using one ormore probing devices; measuring a first leakage current associated withthe operating voltage; determining if the measured first current ishigher than a first predetermined amount, categorizing the device as aninitial failure if the measured first current is higher than the firstpredetermined amount; storing a first indication associated with theinitial failure if the device has been categorized as the initialfailure; applying a second voltage to the gate of the test patterndevice of the semiconductor wafer if the measured first current is belowthe first predetermined amount; measuring a second leakage currentassociated with the second voltage using one or more probing devices;categorizing the device as an extrinsic failure if the second measuredleakage current is higher than a second predetermined amount; storing asecond indication associated with the extrinsic failure if the devicehas been categorized as the extrinsic failure; categorizing the deviceas a good device if the second measured leakage current is below thesecond predetermined amount; and storing a third indication associatedwith the good device, if the device has been categorized as the gooddevice.
 2. The method of claim 13 wherein the operating voltage rangesfrom about 1.3 to about 3.3 volts.
 3. The method of claim 13 wherein thesemiconductor wafer is a partially completed wafer including a scriberegion.
 4. The method of claim 13 wherein the gate of the test patterndevice is overlying a dielectric layer, the dielectric layer having athickness of about 40 Angstroms and less.
 5. The method of claim 13wherein the one or more patterns comprises one or more MOS transistorstructures having a channel width of about 95 nanometers and less. 6.The method of claim 13 wherein the measuring of the first leakagecurrent is provided using one or more other probing devices.
 7. Themethod of claim 13 wherein the one or more probing devices is coupled toa test station.
 8. The method of claim 13 wherein the storing of thefirst indication or the storing of the second indication or the storingof the third indication is provided using one or more memories coupledto a test system.
 9. The method of claim 13 wherein the initial failureis a total failure.
 10. The method of claim 13 wherein the good deviceis within an acceptable operating specification.
 11. The method of claim13 wherein the first determined amount ranges from about a first amountto about a second amount for the semiconductor wafer having one or moreMOS transistor structures having a channel width of about 95 nanometersand less.
 12. The method of claim 13 wherein the second determinedamount ranges from about a first amount to about a second amount for thesemiconductor wafer having one or more MOS transistor structures havinga channel width of about 95 nanometers and less.
 13. A computer-readablestorage medium storing a plurality of instructions for testing asemiconductor wafer using an in-line process control, the plurality ofinstructions comprising instructions that cause the processor to: applyan operating voltage on a gate of a test pattern on a semiconductorwafer using one or more probing devices; measure a first leakage currentassociated with the operating voltage; determine if the measured firstcurrent is higher than a first predetermined amount to indicate aninitial failure; determine if the measured first current is below thefirst predetermined amount to indicate that the device is subjected to asecond voltage; apply the second voltage on the gate of the test patternon the semiconductor wafer; measure a second leakage current associatedwith the second voltage; determine if the second measured leakagecurrent is higher than a second predetermined amount to indicate thedevice is an extrinsic failure; determine if the second measured leakagecurrent is below the second predetermined amount to indicate the devicea good device.